1. Technical Field
The invention relates to a spectroscopic sensor and a method tor manufacturing the same.
2. Related Art
In the medical, agricultural and environmental fields, spectroscopic sensors are need to diagnose or examine target objects. In the medical field, for example, pulse oximeters are used to measure a blood oxygen saturation level by absorption of light by hemoglobin. In the agricultural field, saccharimeters for measuring the sugar content of fruits by absorption of light by sugar are used.
JP-A-2011-185634 discloses a spectroscopic sensor including a photosensor unit, an angle restricting filter and a spectroscopic filter. The angle restricting filter restricts the incident angle of incident light entering a light-receiving region of the photosensor unit. The spectroscopic filter is formed by a thin multilayer formed on a slope structure provided on the angle restricting filter, The slope structure is formed by a CMP (Chemical Mechanical Polishing) method.
In the above-described spectroscopic sensor, however, it may not be easy to form a slope structure with an accurate angle by the CMP method. Accordingly, there are cases where the spectroscopic filter is not formed easily.